Left: Distribution of the hydrogen volume density (n_H), derived from the Leike et al. (2020) 3D dust reconstruction, for the distance channel that shows the highest correlation with the gas column density (N_H) derived from the Planck observations, shown by the contours. The white contours correspond to N_H = 1, 2, 3, 4, 5, 8, and 12.5 × 10²¹ cm⁻². Right: Distribution of the projected Rayleigh statistic (V, Eq. (4)) in 5 × 4 blocks across the map. The minimum of the color bar is set to 2.87, which is roughly equivalent to a 3σ significance for this indicator of the correlation between the two images. The green disk indicates the derivative kernel size Δ = 30′.